UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

REGION 8 

Ref: 8P-AR 

Mr. Gordon Pierce, Program Manager 

1595 Wynkoop Street 

DENVER, CO 80202-1129 

Phone 800-227-8917 

http://www.epa.gov/region08 

MAR 1 3 2015 

Technical Services Program-Air Pollution Control Division 

Colorado Department of Public Health and Environment 

4 3 00 Cherry Creek Dr. S. 

Denver, Colorado 80246-1530 

Re: 2013 and 2014 Annual Monitoring Network Plan 

Dear Mr. Pierce: 

Thank you for submitting the 2013 and 2014 Colorado Annual Monitoring Network Plans (AMNP) 

dated June 28, 2013 and July 1, 2014, respectively. EPA Region 8 has reviewed the submitted 

documents and found that all of the requirements specified in 40 CFR Part 58.10, as well as the 105 

grant commitment to prepare a plan annually, have been met with the submission of these documents, 

with the exceptions to 40 CFR Part 58 Appendices A, D and E noted in the enclosure to this letter. 

When AMNPs propose changes to the SLAMS monitoring network, the EPA regional office is required 

to approve or disapprove the planned SLAMS changes. Region 8 has reviewed the submitted documents 

and the planned changes. Region 8 is approving the 2013 network changes detailed in the 2013 plan 

(termination of monitoring at Rist Canyon and inception of PM2.s monitoring at Castlewood Canyon 

State Park) and is also approving the following proposed changes detailed in the 2014 plan: 

1. Shutdown of the Highland Reservoir monitoring site during construction, with potential 

relocation 

2. Installation of meteorological sensors at the Colorado Springs Highway 24 site 

3. Installation of a Second Near Roadway N02 monitoring site at I-25/Acoma Street and 49th 

A venue in Denver 

4. Waivers of 40 CFR Part 58, Appendix E Section 4 and 5 siting requirements with respect to trees 

near the CAMP and Welby monitoring sites 

5. Cessation ofPb sampling at Centennial Airport (pending a network modification request with a 

historical data assessment that includes 2014 data) 
The enclosure also includes three minor discrepancies which should be addressed in your 2015 AMNP 

and considerations for the S02 Data Requirements Rule. If you have any questions or comments, contact 

me at (303) 312-6416 or Richard Payton of my staff at (303) 312-6439. 

Enclosure 

cc: Pat McGraw, CDPHE 

Greg Harshfield, CDPHE 

Carl Daly, Director 

Air Program 
Enclosure 

1. Highland Reservoir shutdown: 

EPA understands this site is unavailable for an extended period of time due to construction in the area. 

EPA will work with CDPHE as needed in the future to either reinitiate monitoring at this site or to find a 

new location for monitoring in this area. In the meantime, EPA is approving the shutdown of this 

monitoring site. 

2. Colorado Springs Highway 24 meteorological monitoring: 

Since CDPHE learned that this site would continue to be available as a monitoring location for the 

longer term, the state decided to add meteorological monitoring at this site. EPA understands that the 

meteorological data collected at this site will be more representative for the monitoring data than the 

available airport meteorological site; therefore EPA is approving this network modification. 

3. Near Road N02 monitoring: 

For the second Denver Core Based Statistical Areas (CBSA) near roadway NOz site, 40 CFR Part 58, 

Appendix D Section 4.3.2(a)(l) specifies that: 

Where one CBSA is required to have two near-road NOz monitoring stations, the sites shall be 

differentiated from each other by one or more of the following factors: fleet mix; congestion 

patterns; terrain; geographic area within the CBSA; or different route, interstate, or freeway 

designation. 

When inspected by EPA monitoring staff from Region 8 and the EPA Office of Air Quality Planning 

and Standards (OAQPS) in December 2014, the EPA determined that while both the existing near 

roadway site and the proposed second site lie along I-25 within 4 miles of each other, the second site 

differs from the first with respect to fleet mix (6.3% trucks at 81

h Avenue, 10.9% trucks at 491

h Avenue); 

congestion patterns; and terrain (8th Avenue is less than 10 feet above the level ofthe Platte River, while 

49th Avenue is more than 50 feet above the level ofthe river, outside the immediate channel). In 

addition, the 49th Avenue site is within the Globeville area, and will measure near roadway NOz in an 

area identified in public comment letters to the Colorado Department of Public Health and Environment 

(CDPHE) as a local community concern. The two sites also present differences with respect to their 

relative proximity to the Denver central business district and major NOz point sources north of that 

district. Finally, the 49th Avenue location, 1 mile east-northeast ofthe La Casa NCore site, presents 

opportunities for comparisons of data collected within 5 meters of the nearest freeway lane to data from 

a nearby site approximately 400 meters from the nearest freeway lane. Therefore, the EPA is approving 

the installation ofCDPHE's second near roadway NOz monitoring site at I-25/Acoma Street and 49th 

A venue in Denver. 

4. Siting Requirements Waiver: 

Regarding the waiver of siting requirements with respect to trees which have grown over the years near 

the CAMP and Welby monitoring stations, both CAMP and Welby are among the longest continuously 

operated air monitoring stations in Colorado. CAMP is one of the longest running in the country, with 

CO, NOz and S02 data in AQS extending back to 1965. The EPA recommends CDPHE continue 

operation of each monitoring site, while acknowledging potential issues resulting from the nearby trees. 

In addition, the Welby station has been identified by the EPA as one ofthe 40 N02 sites nationwide 

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providing the data required by 40 CFR Part 50, Appendix D, Section 4.3.4(a) (Regional Administrator 

(RA) Required Monitors), where "siting these monitors in locations to protect susceptible and vulnerable 

populations" is accomplished. Therefore, both waiver requests are approved. 

Similar to the growth of trees at Welby and CAMP and the waiver approval for those trees provided 

herein, staff of the EPA have noted that the pine tree on the east side of the Boulder Chamber of 

Commerce site may also need a waiver of the 40 CFR Part 58, Appendix E Section 4 and 5 siting 

requirements for continued operation. CDPHE may wish to include a waiver request for that site in the 

2015 AMNP. 

5. Lead Monitoring: 

Lead monitoring at Centennial Airport, which was initiated in 2010, was based on early emission 

calculations showing that annual lead emissions from aircraft operations at Centennial exceeded 1 

ton/year. The monitoring requirement in Appendix D, Section 4(a) calls for monitoring at "each airport 

which emits 1.0 or more tons per year based on either the most recent National Emission Inventory 1 or 

other scientifically justifiable methods and data (such as improved emissions factors or site-specific 

data)." National Emission Inventory (NEI) data for Centennial Airport lead emissions were 0.73 tons in 

the 2008 NEI, and 0.83 tons in the 2011 NEI, so lead monitoring is no longer required at Centennial 

unless alternative scientifically justifiable methods and data indicate recent emissions were in fact 

greater than 1 ton/year. 40 CFR Part 58, Appendix D, Section 4.5(a)ii allows the EPA RA to waive 

source oriented lead monitoring requirements if state monitoring agencies can demonstrate that 

emissions from the lead source targeted by a source oriented monitor will not contribute to 

concentrations in ambient air greater than 50% of the lead National Ambient Air Quality Standard 

(NAAQS, 0.15 f.lg/m3

, 3 month average). Lead data collected at Centennial in 2010 through October 

2014 show no three month average lead above 0.02 f.lg/m3• If fourth quarter 2014 data, not yet in AQS, 

show comparable levels, then CDPHE could use this data to complete the network modification request 

submitted March 9, 2015 in accordance with Appendix D, Section 4.5(a)ii. 

Exceptions to 40 CFR Part 58, Appendices A, D and E compliance: 

In addition to proposed changes to the SLAMS network which require EPA regional office approval, 

AMNPs are required in 40 CFR Section 58.10 "to provide evidence that siting and operation of each 

monitor meets the requirements of Appendices A, C, D, and E of this part, where applicable." While 

CDPHE's 2013 and 2014 ANMPs in general provide this evidence, instances in which the current 

CDPHE ambient air monitoring network is not compliant with 40 CFR Part 58, Appendices A, D and E 

have been identified during the EPA regional office review of the plans and are described below. The 

EPA recommends that CDPHE review these exceptions and work toward a resolution to ensure 

monitoring network compliance. 

PM2.s Precision: 

Specifically, 40 CFR Part 58, Appendix A, Section 3.2.5.1 requires that each designated PM2.s 

Federal Reference Method (FRM) and Federal Equivalent Method (FEM) used in a monitoring 

network have 15% ofthe sites using each method collocated with a second precision sampler. 

The EPA notes that the PM2.s monitors at Cortez and Castlewood Canyon State Park use the 

Partisol2000 manual FRM PM2.s samplers, but neither they nor any other site in the CDPHE 

1 NEI data available at http://www.epa.gov/ttnlchief/eiinformation.html 

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network has a collocated pair of Partisol 2000 samplers. The Cortez and Castlewood Canyon 

data therefore do not have any precision data with which the data collected by the samplers can 

be validated. The data from the monitors is not accompanied by appropriate quality assurance 

data which would allow the data to be used for regulatory purposes. EPA recommends that an 

additional Partisol 2000 of the same method type be deployed at a site already using the Partisol 

2000 method in order to collect a collocated sample every 12th day as required by Appendix A. 

Alternatively, the Partisol2000 sampler(s) in the network could be replaced with Partisol 2025 

samplers, which already meet Appendix A collocation requirements. EPA notes that even 

though the Castlewood Canyon State Park site was included in the 2013 and 2014 plans, as of 

January 1, 2015, the site is no longer in operation per CDPHE's network modification request, 

thereby resolving this issue for that site. 

NCore PMto-2.s: 

Appendix D, Section 3.2(b) requires PMI0-2.5 monitoring at NCore, and has since Jan. 1, 2011. 

That data must be collected with an FRM as defined in 40 CPR Part 50, Appendix 0 2 or with an 

approved FEM for PMI0-2.5, and must be reported to AQS under parameter code 86101. CDPHE 

has no data under parameter code 86101 in AQS from any site. If the paired Partisol2025 PM10 

and PM2.5 samplers at La Casa meet the requirements of 40 CPR Part 50, Appendix 0, then 

historical PMI0-2.5 from La Casa should be calculated back to September 2012, when monitoring 

at La Casa began, and loaded into AQS. 

PM2.s FEM operation: 

Another requirement for AMNPs, added to 40 CPR Part 58 as part of the 2013 PM2.s NAAQS 

Revision Rule,3 regards PM2.5 FEM monitors. Sections 58.10(b)(13) and 58.ll(e) were added to 

allow state and local monitoring organizations to document poor performance of PM2.5 FEM 

methods in comparison to PM2.5 FRMs, and, through a request in the AMNP, ask for EPA 

approval to exclude the FEM data from comparisons to the NAAQS for regulatory 

determinations. 4 

CDPHE operates five Thermo Scientific FDMS TEOMs, some or all of which are designated as 

PM2.5 FEMs. While the equipment meets the specification of the FEM designation, CDPHE has 

operated those monitors in a manner not identical to that specified in the FEM designation from 

EPA Office of Research and Development. CDPHE's operational modifications ofthe monitors 

predates the designation of the monitors as FEMs in June of2009. 

2 40 CPR Part 59, Appendix 0, Reference Method for the Determination of Coarse Particulate Matter as 

PMI0-2.5 in the Atmosphere. 

3 78 FR 3229-3230, 3234, and 3241-3244, January 15,2013, Final Rule, National Ambient Air Quality 

Standards for Particulate Matter. 

4 78 FR 3230: "The revised monitoring rule, promulgated today in conjunction with the PM NAAQS 

revision, includes, as proposed, language allowing monitoring agencies to identify P M2.5 FEMs that are 

not providing data of sufficient comparability to the FRM and, with EPA approval, to allow such data to 

be deemed ineligible for comparisons with the PM2.s NAAQS"; 78 FR 3242: "The proposal also 

provided that the EPA Regional Administrator would be responsible for approving annual monitoring 

network plans where agencies have provided a recommendation that certain PM2.5 FEMs be considered 

ineligible for comparison to the NAAQS." 

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While we understand that CDPHE is not pursuing use of the FDMS TEOMs for PM2.s NAAQS 

comparison, in order to allow EPA Region 8 to approve CDPHE's use ofFDMS TEOMs solely 

for AQI purposes, EPA requests that FEMs used in the CDPHE network be identified in the 

20 15 ANMP in accordance with Section 58.1 O(b )( 1.3 ), and that the detailed technical data of 

Section 58.11(e) be provided for the instruments as currently operated (perhaps as an appendix to 

the plan). In addition EPA requests a description of the current operation, noting deviations from 

the FEM operation, and the rationale that led to CDPHE to modify the operation. With this data, 

EPA could then approve CDPHE's current practices. 

Items to be addressed in 2015 AMNP: 

Three minor discrepancies were noted in the EPA review of the 2014 AMNP. First, Page 22 defines 

NAAQS exceedances in the same manner as 40 CFR Section 50.1(1), and page 28 says "there were no 

PM2.s exceedances recorded in the Western Slope region [in 2013]. The maximum 24-hour 

concentration at Powell42.2 )lglm\ [sic] and the annual average was 8.8 ug/m3

, though the average did 

not satisfy summary criteria." The 42.2 )lg/m3 value, and 3 others in 2013 at the Powell station were all 

exceedances ofthe 24-hour PM2.s NAAQS, contrary to the statement that there were no exceedances. 

Second, page 18 ofthe 2014 AMNP discusses the Denver Metropolitan Statistical Area (MSA) and 

Primary Metropolitan Statistical Area (PMSA), and the number of MSAs in CDPHE. 40 CFR Part 58 

uses the CBSAs and Combined Statistical Areas (CSAs) defined by the Office of Management and 

Budget (OMB) to define monitoring requirements. The term MSA is still used by OMB, but PMSA is an 

obsolete term and definitions of PMSAs are no longer available from OMB. In addition, with new 

CBSA definitions from OMB in 2013, Colorado now has 7 MSAs, not the 6listed in the 2014 AMNP, 

and the Denver CBSA (or MSA) consists ofthe counties listed in the 2014 AMNP (Adams, Arapahoe, 

Broomfield, Denver, Douglas, and Jefferson), plus Gilpin, Clear Creek, Park and Elbert counties. We 

recommend that CDPHE review the new CBSA and CSA definitions from OMB and assess whether the 

existing and planned CDPHE monitoring network continues to meet the Part 58 requirements given 

those new definitions. EPA Region 8 staff provided Network Assessment training, including this 

consideration, at the 2014 National Air Monitoring Conference in Atlanta, with the training material 

available at http://www .epa.gov/ttnamti 1/fi.les/20 14conference/monn@ayton.pdf 

Third, page 29 of the plan says "The APCD does not collect or report PM2.s FEM data." GRIMM FEM 

PM2.s data has been collected and reported to AQS by CDPHE since April of2013. For the 2015 AMNP 

and Network Assessment, we recommend that CDPHE review these items and update the information as 

appropriate. 

S02 Data Requirements Rule considerations: 

Finally, in 2015, the second five-year Network Assessment specified by 40 CFR 50.1 O(d) will be due. A 

few things you may want to consider during this assessment are the potential implications of the 

proposed S02 Data Requirements Rule (http://www.gpo.gov/fdsys/pkg/FR-2014-05-13/pdf/2014-

09458.pdf) and consent decree approved by the U. S. District Court for the Northern District of 

California on March 2, 2015, and which I forwarded to Will Allison by e-mail on that date. 

The Rule proposal includes several possible threshold options for point sources, which would require 

monitoring or modeling, including EPA's preferred option of: 

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1) Actual emissions over 2,000 tons/yr; and 

2) 1,000 tons/yr in cities over 1,000,000 population. 

If finalized as proposed, the Rule would require monitoring or modeling data for point sources over 

these thresholds to inform future designation decisions. By January 15, 2016 states must identify the 

sources above these thresholds and determine whether modeling or monitoring (at each source) will be 

used to evaluate area NAAQS compliance. For sources states choose to characterize by modeling, 

modeling protocols would be due to the Regional Office at that time as well. For sources states choose 

to characterize with monitoring data, required siting information about monitoring stations would be due 

to Regional Office by July 1, 2016. 

Under the terms of the final consent decree, EPA will designate areas that have existing monitored 

NAAQS violations, areas that have sources greater than 16,000 tons of S02 emitted in 2012, and areas 

that have sources emitting greater than 2,600 tons and an annual average S02 emission rate of 0.45 lbs 

S02/MMBtu or greater (2012 data) within 16 months of the consent decree approval on March 2, 2015. 

EPA will then designate the remainder of the country by December 31 , 201 7 unless monitoring to 

characterize a point source has begun in an area by January 1, 2017. Areas with newly installed source 

monitors (by January 1, 2017 or sooner) would be designated in 2020. 

The combined impact ofthe Final Rule, to be published sometime in 2015, and the consent decree, will 

leave little time for decisions, monitoring network planning, and potential collaboration with sources. 

Therefore, including potential S02 designations monitoring in the 2015 network assessment might give 

states an opportunity to get ahead on the planning, while looking at non-binding options prior to the 

2016 deadlines. 

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